The image is in natural colors, more or less — the camera used blue, yellow, and red filters to get the image, plus a filter tuned to a narrow range of colors that are emitted specifically by warm, glowing hydrogen gas. That’s the ruby red color you see in the galaxy. Can you see how the gas seems to follow the spiral arm? That’s because the gas in the galaxy piles up along that pattern as the galaxy rotates (see point #8 in that link specifically). It gets compressed and forms new stars. When these stars turn on, they heat up the gas, exciting the electrons in the hydrogen atoms. The atoms respond by emitting light around 656 nanometers, in the red part of the spectrum. Scientists call this specific wavelength "hydrogen alpha", or just H-alpha for short (or Hα for shorter). When you detect it, it’s a sure sign you’re seeing hydrogen gas being poked by some process. It may not be a star; we see it emitted by hydrogen in supernova debris, and in the swirling disks of matter near a black hole, and in the regions where gas clouds violently collide.

But most of the time, the vermillion glow of Hα is from the swaddling cloth of gas still surrounding the wailing newborn stars formed from it. Because of this, we can see these fledgling stars even from millions of light years away; in the case of galaxy M83, from 15 million light years away: 150 quintillion kilometers (90 quintillion miles) remote!

One of my favorite aspects of the Universe is not only that we can see it, but that in many cases it’s so easy to see it, and to study it. That image of M83 was composed of four exposures totaling less than two hours, and constructed by one person — David De Martin from Sky Factory. Certainly, he had help: the telescope was built by dozens of engineers, hundreds of workers, managed by scores of people at the ESO, and is the end product of a long line of work by hundreds of other people. The pedigree of that image is lengthy and arguably stretches back to the first humans who looked up at the sky.

But here we are, thousands of years later, and we’re still looking up. Our tools are a lot better now, as is our understanding, and I’m very, very glad for people like Davide and others at the ESO, who strive to stretch our knowledge of the Universe — and our appreciation of its beauty — even further.

I love when you post pics like these. I follow the link and grab the full-res and start exploring beyond the focus of the image itself. There’s so many little swirls and whorls in the background that I assume are other galaxies. It’s really awe-inspiring seeing the foreground object in comparison to the tiny few-pixel wide galaxies that rival its size or are even larger were they to be near each other. It really brings the vastness of it all into perspective.

Phil:
What do you make of the disruption in the upper right hand side of the image? It looks like somebody stole a gazillion stars over there!
– Free Hydrogen sucked out of the area by a galactic merger?
– Free Hydrogen made into new stars long ago in a paroxysm of star formation and therefore not around now to make new stars? (By another galactic merger.)
– Intervening dark dust cloud blocking the light?

Poul Anderson wrote a pretty good story(Tau Zero) about a space craft powered by Bussard collectors that could make that trip in about 15.0001 million years. Unfortunately, their Tau is very close to zero, their decelerator is broken so they can’t slow down, only accelerate, so they zip thru the galaxies , constantly getting closer to Tau Zero(ie, light speed). It’s an interesting yarn, available at WOWIO and can be read on line for free.

Damnit, context FAIL. I saw the title of your post and thought the “laptronica” musician had maybe released a new album named “Nursing Arms”. Instead all I get is a really cool picture and links to learn about a galaxy. Wait… that’s not a FAIL at all!

@ Gary
When you commented about Poul Anderson’s Tau Zero it twigged my memory. I had to run to my book shelves and sure enough I have the original paper back printing of it. I bought it in 1971 and what I remember it was an impressing story to my young mind. A cover forward was written by James Blish. A short story version was originally published in Galixy Science Fiction in June and August 1967 under the title “To Outlive Eternity”.
I will now gently put my copy back as I never throw out a novel and my old paperbacks are getting pretty yellow and frail. (sort of like me)

No, no, no. There’s a very easy explanation for that. Yes, the galaxy is that far away, but the light associated with it was created all at once in an initial stream of photons connecting the galaxy to Earth. That way, everything can still have been created all at once, and the photon stream is continuous, so we don’t need to wait 15 million years for the light to get from M83 to Earth! See, very simple. No need for changing the laws of physics at all!

Those same creationists revise the laws of physics and say the speed of light has slowed down over time.

Somebody ought to point out to those silly creationists’ what Montgomery “Scotty” Scott said in Star Trek: TOS — “The Naked Time”: “Capt’n, I cannae change the laws of physics… I’ve gotta have thirty minutes!”

No, no. You’re getting it wrong again. The Creator has always been and and will always be. He/She/It exists beyond time. There is no need for anyone/anything to create the Creator. You clearly need guidance. Might I suggest paying a visit to your nearest YEC church.

I’m surprised that no-one (Nathan) has popped in to say that where the BA mentions gas he means plasma.

CanadianLeigh, I know what you mean about hoarding old books. I have been politely asked to put all my old books into storage. I’m allowed to keep them, just not stacked up around the apartment. So I’m finally getting the chance to catalog some old gems I’d forgotten I’d read including a stacks of Poul Anderson, Asimov, Clarke, Heinlein and other grand masters. Found some crap too. Who new I actually own something by Jackie Collins.

I’ve already given up on the RSS (Really Slow Service!) Feeds because they tend to arrive several hours late at the best of times. Far better to bookmark a direct link to Bad Astronomy on one’s browser toolbar.

CanadianLiegh:
At the time I read Tau Zero,(two weeks ago) I had just discovered WOWIO and was able to read it online for FREE.!!! A few days later, I received my copy of Greg Bears book City at the End of Time, which posits the exact opposite scenario, in which humans 100 trillion years down the line are struggling to survive the dissolution of all matter, etc. I really liked the juxtaposition of those two points of view,,,

Of course, Andersons book was written long before we discovered the accelerating expansion of the universe. It was based upon the cyclical theory of the universe.
Gregs story wonders what it would be like when that expansion becomes really significant,,,

I’m with Sirian on this. Google reader is a lot more convenient than keeping bookmarks, but if I only get the first few lines of every post I can’t use it. Usually when you change anything on your blog you tell your readers about it and what your reasons are. This is a sudden and unannounced thing, so I’m guessing the Discovery guys are responsible and didn’t tell you. I hope you can change it back.

@shane: Everybody who reads comments at all knows, now, that Phil’s pulling a fast one. I will mention that the “gas” could not “slam” (presuming that’s what’s really going on at all) if it were not ionized; it would just pass right through, because it’s what in the lab we would call a “hard vacuum”, and gas particles barely interact unless they actually collide. Plasma particles, by contrast, interact at macroscopic distances, so it really matters that, and how much, these “gases” are ionized.

@Nathan: I will mention that the “gas” could not “slam” (presuming that’s what’s really going on at all) if it were not ionized; it would just pass right through, because it’s what in the lab we would call a “hard vacuum”, and gas particles barely interact unless they actually collide.

OK, I’ll bite; what’s the mean free path of a gas particle (atom or molecule) in the ISM (interstellar medium)? Just an order of magnitude estimate will do thanks.

Oh, and I checked and Phil’s blog does not use the word “slam” … where did you quote it from, may I ask?